The challenge, designed to raise funds for amyotrophic lateral sclerosis through $100 donations, has attracted the support of celebrities, media personalities and world leaders alike.

Although it typically involves a person nominating three "friends" after pouring a bucket of ice over their own head and donating $100 to ALS research, Mr Gatto elected to challenge the top cop, the Premier and Mr Mitchell, who has been outspoken against his character.

It's the second time Mr Gatto has taken aim at the Premier in less than a week after describing him as "unelected" in response to Dr Napthine saying he should get out of boxing. Mr Gatto was stripped of his promoter's licence last year but has continued to be involved in the sport, recently helping arrange sponsorship for a high-profile fight.

The mediator and debt collector said he chose his nominations "just for a bit of fun". "I think it's a great gesture, it's for a great cause and I think it's a step in the right direction," he said.

Mr Gatto was portrayed as a key character in the first season of Channel Nine's Underbelly drama series, which was based on the gangland war that played out in Melbourne in the late '90s. He was acquitted of murdering gun-for-hire Andrew Veniamin in 2005 after successfully arguing he shot Veniamin in self-defence.

3AW's Neil Mitchell emphatically rejected the nomination. "I will have nothing to do with anything Mick Gatto is involved in," he said.

Former US president George W. Bush, fictional television character Homer Simpson, Hollywood's Matt Damon and Ben Affleck and Victorian opposition leader Daniel Andrews are among those who who have gone under the ice for charity.